Winches are used to retrieve line and to provide hauling forces such as is needed to deploy mooring lines, floats, buoys, and vehicles onto the deck of a ship. Shipboard winches generally require secure placement to adequately handle heavy load demands and to resist the constant motion of the seas. For this reason, it is common practice for shipboard winches to be secured to base plates which are permanently welded to the deck of the ship. The installation of winches and winch mounting systems or repositioning or adjustment of the winch angle following winch installation generally requires a robust hoist or other lifting means to elevate, move, or rotate the apparatus into position.
Because deck space is limited on ocean-going vessels, and once installed, repositioning of winches is difficult if not impossible during a voyage, base plates are generally custom fabricated for a specific voyage, taking into account the likely orientation and location of use of the winches for that specific operation. The custom base plates are then welded to their specified position on the deck, and the winch is firmly attached for the duration of the time at sea. Subsequent missions may require different winch positions which results in the disposal of the customized base plates as well as a loss of time, labor, and money.
During operation, a winch is often used in conjunction with sheaves and/or flanges. In order to ensure minimum stress and wear on the winch line, it is preferable to maintain an optimal fleet angle (i.e., the angle of the winch line between the sheave and the drum of the winch). In most cases, the optimum fleet angle is ninety degrees (e.g., the winch line is perpendicular to the winch drum). Therefore, the base plates must be precisely designed and positioned to ensure that the desired angle is achieved when the mounted winch is in use.
Winch fixation to the platform prohibits repositioning while at sea and significantly reduces the adaptability of a winch for multiple uses, often resulting in the need for multiple winches in order to accommodate a variety of shipboard hauling needs. Consequently, it is not uncommon that more than one size or type of winch must be mounted on deck in order to complete specific shipboard tasks, but installation requirements severely limit the potential number of different winch types which may be used. Likewise, the presence of installed winches also limits the deck space available for other equipment.
Cranes are sometimes used to supplement the hauling needs of the ship. In most cases, a crane is permanently mounted to a specific portion of the deck and requires significantly more space to reliably support the boom. Although cranes have been previously associated with motorized turntables, such turntable assemblies and undercarriages used must be structurally reinforced in order to accommodate the height and weight requirements. The heavy duty nature of these turntables and their associated reinforcing structures necessitates that they occupy a high-relief from platform to the upper mounting surface. Thus, because of size and mounting requirements, crane-associated turntables 1) have a high relief (often greater than 1, 2, or 3 feet from the platform), 2) are not generally mission-portable, 3) require motorized power for operation, and 4) have a large footprint (typically greater than 4, 5, 10, 15, or 20 feet across), and furthermore are not generally suitable for support of a stand-alone winch without a boom. In contrast, the compact profile of a boom-less winch renders it more preferable to be mounted on a low-relief, portable turntable.
It would be of great value to have a portable turntable that can attach securely enough to the deck to handle the motions of the seas but can also be detached on site for movement elsewhere on the deck or to another platform. Additionally, an ability to instantly orient the angular position of a shipboard winch or to exchange winches on a single turntable would be advantageous.
While many other known turntables have been described, all rely on gear train and motor assemblies for rotational repositioning. Other described turntables of the art, particularly those of high-relief, must be mounted in a designated area or recessed cavity, limiting their portable aspects. The ability to rotate a heavy-duty turntable by hand minimizes fabrication costs and power requirements (i.e., by eliminating a motor) and time and complexity to reorient during use. Manual rotation consumes no power which is a commodity at sea and gives more precise control of rotation to obtain the optimum fleet angle.
Therefore, a need exists for a versatile winch mounting system that can accommodate the variety of winches brought aboard a ship, thereby mitigating the need for a specific mounting system for each winch type. This relieves space and reduces weight limitations while allowing more equipment to be available for deck use with less required infrastructure.